PPI5 DCC Model Railway Points Position Indicator - 8 Points

About the Product

The BLOCKsignalling PPI5 is a model railway points position indicator for DCC accessory decoders and common-positive point-control systems, monitoring up to 8 sets of points and displaying their last operated position using LEDs on a control panel or route mimic.

The PPI5 is designed for systems where the point motor has a positive common connection, as commonly used with DCC accessory decoders. When the points are operated, the module detects the switching signal and automatically updates the corresponding LED indication.

The module provides 16 input channels for monitoring up to 8 sets of points. Only the LED representing the most recently operated position remains illuminated, providing a clear indication of the last selected route.

Each change is automatically stored in memory, so when power is switched off and restored, the panel LEDs return to their previously recorded states.

Key Features

• Monitors up to 8 sets of points.
• Provides 16 points-monitoring input channels.
• Designed for common-positive point-control systems.
• Ideal for use with suitable DCC accessory decoders.
• Displays the last operated point position using control-panel LEDs.
• Automatically remembers point positions when power is switched off.
• Adjustable LED brightness.
• No external resistors required for standard individual LED connections.
• Opto-isolated points-monitoring inputs.
• Built-in input and memory diagnostic LEDs.
• Suitable for model railway control panels and route mimic boards.
• Supports alternative red and green LED arrangements.
• Compatible with suitable common-anode dual-colour LEDs.
• Optional programming with no programming required for normal operation.
• Built-in LED lamp test function.
  

Points Position Indication

The PPI5 monitors the switching signals applied to the point motor and uses them to determine the last operated position.

Each set of points uses a pair of inputs. When one input is activated, its associated indication LED is selected and the other LED in the pair is switched off. The selected indication remains displayed until the points are operated in the opposite direction.

DCC Accessory Decoder Wiring

The PPI5 is particularly suitable for DCC accessory decoders with a common-positive point-motor connection. The module monitors the point-motor outputs while allowing the accessory decoder to continue operating the points normally.

The diagram shows the connections for one set of points. Connections to the PPI5 can normally be made at the control panel to minimise wiring lengths.

Points Switches & CDU Wiring

The PPI5 can also be used with conventional points switches and a Capacitor Discharge Unit (CDU).

When using this arrangement, a CDU must be used to prevent damage to the PPI5, and the PPI5 and CDU should use separate power supplies. The point-motor common connection must be positive for the PPI5.

Control Panel LED Indication

Red and green LEDs can be installed on a model railway control panel or route mimic to provide a clear visual indication of the last operated position of each set of points.

For the standard individual LED arrangement, external series resistors are not required, as LED brightness is controlled by the PPI5's microprocessor.

The LEDs must be connected with the correct polarity. Incorrectly connecting them in reverse can cause the LEDs to illuminate very brightly, fail and potentially damage the PPI5.

Alternative arrangements using two LEDs per output or common-anode three-wire dual-colour LEDs are also supported. These alternative arrangements require resistors, typically around 1kΩ, to balance the red and green LED brightness.

Automatic Position Memory

Each time the PPI5 detects a change in point position, the new state is automatically stored in memory.

When the module is switched off and subsequently powered again, the LED outputs automatically return to their last recorded positions.

Diagnostic LEDs

Built-in diagnostic LEDs provide useful information during installation and operation.

The yellow IP LED flashes whenever a point operation is detected. The red uP LED indicates that the microprocessor is operating and flashes when a changed point position is recorded in memory.

Important Wiring Information

Keep the control-panel LED wiring separate from the high-current point-motor wiring. This helps prevent interference from the points wiring affecting the low-level LED signals and reduces the risk of damage to the PPI5.

Electrical Requirements

• Power supply: Regulated 12V DC.
• Typical current consumption: Approximately 0.25A.
• Recommended power supply rating: 0.5A to 1A.
• Number of inputs: 16.
• Points capacity: Up to 8 sets of points.
• Input type: Opto-isolated.
• Point-control configuration: Common positive.
• Standard LED resistors: Not required.

The PPI5 should be powered from a suitable 12V DC plug-top power supply. The manual advises against using unsuitable auxiliary outputs from train controllers, as these may not provide sufficiently smooth or stable power.

Documentation & Support

For complete installation instructions, DCC accessory decoder connections, conventional points wiring, LED arrangements, programming and troubleshooting guidance, please download the latest instruction manual:

User Instruction Manual